PURPURA LAPILLUS. 335 



■are strongly ridged, the mouth having a thickened outer lip and generally tuber- 

 culated within. Fig. 31, from the Isle of Man, on the contrary, resembles some 

 of those from the Crag, especially from the Butleyan and Icenian zones, in which 

 the lip is but little thickened. As to this Dr. A. W. Cooke informs me that the 

 toothed condition occurs in specimens in his collection from Portugal, and is a 

 common though not a universal feature in British shells, but it is not found, so far 

 as his experience goes, in Purpuras from the Kola fiord or the Murman coast of 

 Russian Lapland, which are thin in texture; moreover, that a similar non- 

 tuberculated form is met with in Iceland, the modification in shape and texture 

 being due, he thinks, to its northern situation. He considers that, as a general 

 rule, the toothed lip occurs in stout, compact, low-spired forms of P. lapillus, while 

 shells with an elongated spire have usually a simple labrum. 



Tar. minor, Jeffreys (?). Plate XXXIV, fig. 33. 



1867. Purpura lapillus, var. minor, Jeffreys, Brit. Conch., vol. iv, p. 277. 



Dimensions. — L. 18 — 22 mm. B. 12 — 15 mm. 



Remarks. — The specimen figured under this name represents a dwarf form not 

 uncommon in the Wexford gravels which may possibly be the var. minor of 

 Jeffreys. The latter, he says, is smaller than the type, more strongly ridged, and. 

 has a shorter spire. Among the Wexford Purpuras some may be noticed 

 corresponding in sculpture with that figured on PI. XI, fig. 5 as variety brevis 

 (see PI. XXXIV, fig. 32). 



Var. ventricosa, nov. Plate XXXIV, fig. 34. 



Dimensions. — L. 33 mm. B. 24 mm. 



Distribution. — Fossil: Icenian Crag : Bramerton. 



Remarks. — This is an unusual and, so far as I know, an unrecorded variety of 

 P. lapillus from the Icenian Crag in the Wood collection at the Norwich Castle 

 Museum. 



Var. incrassata (J. Sowerby). Plate XI, fig. 1 ; Plate XXXV, fig. 1. 



1914. Purpura lapillus, var. incrassata, F. W. Harmer, Plioc. Moll. Gt. Brit., pt. i, p. 117, pi. xi, fig. 1. 



Distribution. — Fossil : Coralline Crag : Boy ton. Red Crag : -passim. Icenian : 

 Thorpe (Norwich). Wexford. Pleistocene : Middle Glacial, Kelsey Hill. 



Remarks. — On Plate XI of the present Memoir I published three figures of 



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